| Environmental impacts of fisheries |
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 In the process of producing food, economic resources, employment, livelihoods and recreation, fisheries modify ecosystems through more or less reversible impacts on the target resource itself (including through overfishing), the species associated to or dependent on it (such as predators or preys), on the trophic relationships within the ecosystem in which the fishery operates, and on the habitat. The fishery sector is expected to reduce these impacts to a minimum that would also be compatible with its own existence. |
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| Destructive fishing practice Destructive fishing practices have also spread in some poor coastal communities (e.g. the use of dynamite and poison) - particularly on coral reefs. Other less conspicuous or debated impacts relate to direct dumping of debris (gear, twine, food containers, plastic bands, etc.) by fishing fleets, including organic pollution by at-sea processing factory ships, coastal pollution of processing plants, contribution to global warming through exhaust fumes and refrigerant gases, and accidental introduction of alien species. |
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| Overfishing is the central problem in fisheries management and must be tackled through better control of fishing capacity and specific resource rebuilding plans. The same set of measures would also improve species composition although it is impossible to exploit the ecosystem without affecting the relative importance of different species. |
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| Selectivity of gear can be improved and impacts on the bottom and habitat can be reduced through better gear technology and improved fishing practices. Ghost fishing can be decreased through greater awareness raising, prohibition and control of dumping of damaged gear at sea, as well as active at-sea programmes for retrieval of lost gear. Gear technology can also contribute in diminishing the fishing capacity of lost gear (e.g. biodegradable material, collapsible traps, etc.). Destructive fishing practices must be further prohibited with stronger enforcement. |
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| Overall, however, the solution is also in generally improving the economic conditions of poor coastal communities and providing alternative forms of livelihood. In general, substantial efforts are needed to improve data collection and research on these issues. |
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| Countries have been tackling overfishing for a long time, although not very successfully. On the institutional side, NGOs have become very active at uncovering and illustrating the problem, exerting considerable pressure on governments and international fishery organizations. An International Plan of Action (IPOA) for the Management of Fishing Capacity was adopted at FAO in 1999 and is currently being implemented. In addition, the FAO IPOA on Illegal, Unreported and Unregulated Fishing (IUU), adopted in 2001 will also contribute to countering overfishing. In order to limit international trade in endangered fishery species, CITES is considering adding fish species subjected to large-scale exploitation to its annexes. The progressive development of ecolabelling practices and the increasing integration of environmental criteria into sustainability criteria for fisheries should also provide additional incentives and fuel consumers' pressure. |
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| On the operational side, much has been done to address the environmental impacts of fisheries. Some countries have regulated discarding, imposing severe quotas, or banning it altogether, forcing the landing of all unwanted bycatch (e.g. in Norway, Canada, Iceland, and the Faeroe Islands). Selective grids, panels and square meshes are used in several trawl fisheries to facilitate the escape of unwanted species or small-sized individuals. Longlines are being modified to reduce bycatch of birds and an IPOA for Reducing Incidental Catch of Seabirds in Longline Fisheries was adopted by FAO in 1999. |
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| Special devices are currently used in tuna fisheries to successfully reduce dolphin catches. Zoning has been conventionally used to keep trawlers away from vulnerable coastal habitats, although with little success in areas with large overcapacity. Marine Protected Areas (MPAs) have become fashionable and if properly enforced could be more effective. In some countries (e.g. Norway), programmes exist to retrieve lost gillnets lying on the bottom. The development of integrated and more sustainable livelihoods programmes are being implemented (e.g. by FAO in Western and Central Africa). Some countries (USA, Ireland) require the elaboration of an environmental impact assessment (EIA) and/or environmental impact statement (EIS) for their fisheries. |
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| Awareness of this issue has been greatly increasing since UNCED (1992) both in the fisheries sector and among the public. The general pressure and progressive evolution towards ecosystem-based fisheries management will facilitate the reduction of environmental impacts. The sector is quite willing to act positively if this can be done in an economically viable way. Progress made in fishing and processing technology is significant and the position of the fisheries sector regarding ecolabelling is gradually improving. As a consequence, while much remains to be accomplished, the prospects for improvement are optimistic. |
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| Some of the more well-documented impacts include: |
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| OverfishingExcessive fishing reduces spawning biomass below optimum levels and catches below the maximum sustainable yield. |
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| The problem, systematically addressed for a century albeit with mixed results, began in the North Atlantic before World War II and spread progressively to the North Pacific in the 1950s, the Eastern Atlantic and Eastern Pacific in the 1960s, the Indian and Antarctic oceans in the 1970s and the South Pacific and Southwest Atlantic in the 1980s - all with very significant economic costs. |
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| Changes in species composition and biodiversity are common with progressive reduction of large, long-lived, and high-value predator species and the increase in small, short-lived, and lower value pelagic and demersal prey species. The process has been coined as "fishing down the food chain". |
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| Important macroscopic changes have been observed in many ecosystems such as the North Sea, Yellow Sea, North Atlantic (e.g. George's Bank and Barents Sea), Gulf of Thailand, and Southeast Australia. In some regions, the abundance of scavenging birds has significantly increased, possibly due to the large quantities of discards. It is now also clear that intensive fishing reduces genetic diversity of wild populations (e.g. rapidly depressing the proportion of fast growing and late spawning individuals). Changes in species composition or dominance can also be provoked through competition for food between fisheries and marine apical predators. |
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| Non-selective fishing gear Use of non-selective fishing gear (e.g. trawls, longlines, gillnets) can take a significant bycatch of juvenile fish, benthic animals, marine mammals, marine birds, vulnerable or endangered species, etc. that are often discarded dead (about 20 million tonnes per year). While bycatch and discard problems are usually measured in the potential loss of human food, the increased risk for particularly vulnerable or endangered species (e.g. small cetaceans, turtles) is significant. In the North Sea, for example, the impact on the food chain and species composition is consequential as discards can represent up to 30% of birds' consumption. |
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| Ghost-fishing Ghost fishing occurs when certain gear such as pots or gillnets continue to kill fish for some time after having been discarded at sea or lost, e.g. in bad weather. |
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| Impacts on the bottom The intense use of trawls and other mobile bottom gear (e.g. dredges) result in changes in bottom structure, microhabitats, and benthic fauna. The effect is particularly obvious when these gears are used in environments such as sea grass and algal beds, coral reefs, sponges, tube worms. The longterm impact is less obvious on soft bottoms although scraping and ploughing the bottom to depths of as much as 30 cm can seriously disturb the substratum habitat and productivity. |
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News Documents Books Multimedia  "Pristina?" La verdad sobre la degradacion de los oceanos "Pristine?" Shifting baselines. The truth about ocean decline. |
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